Commit 7b7a8098 authored by Thibault Saunier's avatar Thibault Saunier
Browse files

v4l2dec: Fix race when going from PAUSED to READY

Running `gst-validate-launcher -t validate.file.playback.change_state_intensive.vorbis_vp8_1_webm`
on odroid XU4 (s5p-mfc v4l2 driver) often leads to:

  ERROR:../subprojects/gst-plugins-good/sys/v4l2/gstv4l2videodec.c:215:gst_v4l2_video_dec_stop: assertion failed: (g_atomic_int_get (&self->processing) == FALSE)

This happens when the following race happens:

- T0: Main thread
- T1: Upstream streaming thread
- T2. v4l2dec processing thread)

[The decoder is in PAUSED state]

T0. The validate scenario runs `Executing (36/40) set-state: state=null repeat=40`
T1- The decoder handles a frame
T2- A decoded frame is push downstream
T2- Downstream returns FLUSHING as it is already flushing changing state
T2- The decoder stops its processing thread and sets `->processing = FALSE`
T1- The decoder handles another frame
T1- `->process` is FALSE so the decoder restarts its streaming thread
T0- In v4l2dec-> stop the processing thread is stopped
NOTE: At this point the processing thread loop never started.
T0- assertion failed: (g_atomic_int_get (&self->processing) == FALSE)

Here I am removing the whole ->processing logic to base it all on the
GstTask state to avoid duplicating the knowledge.
parent e4da670a
......@@ -210,7 +210,6 @@ gst_v4l2_video_dec_stop (GstVideoDecoder * decoder)
/* Should have been flushed already */
g_assert (g_atomic_int_get (&self->active) == FALSE);
g_assert (g_atomic_int_get (&self->processing) == FALSE);
gst_v4l2_object_stop (self->v4l2output);
gst_v4l2_object_stop (self->v4l2capture);
......@@ -266,7 +265,7 @@ gst_v4l2_video_dec_flush (GstVideoDecoder * decoder)
/* Ensure the processing thread has stopped for the reverse playback
* discount case */
if (g_atomic_int_get (&self->processing)) {
if (gst_pad_get_task_state (decoder->srcpad) == GST_TASK_STARTED) {
gst_v4l2_object_unlock (self->v4l2output);
......@@ -334,7 +333,7 @@ gst_v4l2_video_dec_finish (GstVideoDecoder * decoder)
GstFlowReturn ret = GST_FLOW_OK;
GstBuffer *buffer;
if (!g_atomic_int_get (&self->processing))
if (gst_pad_get_task_state (decoder->srcpad) != GST_TASK_STARTED)
goto done;
GST_DEBUG_OBJECT (self, "Finishing decoding");
......@@ -420,6 +419,7 @@ gst_v4l2_video_dec_loop (GstVideoDecoder * decoder)
GST_LOG_OBJECT (decoder, "Allocate output buffer");
self->output_flow = GST_FLOW_OK;
do {
/* We cannot use the base class allotate helper since it taking the internal
* stream lock. we know that the acquire may need to poll until more frames
......@@ -469,25 +469,10 @@ beach:
gst_buffer_replace (&buffer, NULL);
self->output_flow = ret;
g_atomic_int_set (&self->processing, FALSE);
gst_v4l2_object_unlock (self->v4l2output);
gst_pad_pause_task (decoder->srcpad);
static void
gst_v4l2_video_dec_loop_stopped (GstV4l2VideoDec * self)
/* When flushing, decoding thread may never run */
if (g_atomic_int_get (&self->processing)) {
GST_DEBUG_OBJECT (self, "Early stop of decoding thread");
self->output_flow = GST_FLOW_FLUSHING;
g_atomic_int_set (&self->processing, FALSE);
GST_DEBUG_OBJECT (self, "Decoding task destroyed: %s",
gst_flow_get_name (self->output_flow));
static gboolean
gst_v4l2_video_remove_padding (GstCapsFeatures * features,
GstStructure * structure, gpointer user_data)
......@@ -648,7 +633,8 @@ gst_v4l2_video_dec_handle_frame (GstVideoDecoder * decoder,
goto activate_failed;
if (g_atomic_int_get (&self->processing) == FALSE) {
if (gst_pad_get_task_state (GST_VIDEO_DECODER_SRC_PAD (self)) ==
/* It's possible that the processing thread stopped due to an error */
if (self->output_flow != GST_FLOW_OK &&
self->output_flow != GST_FLOW_FLUSHING) {
......@@ -661,10 +647,9 @@ gst_v4l2_video_dec_handle_frame (GstVideoDecoder * decoder,
/* Start the processing task, when it quits, the task will disable input
* processing to unlock input if draining, or prevent potential block */
g_atomic_int_set (&self->processing, TRUE);
self->output_flow = GST_FLOW_FLUSHING;
if (!gst_pad_start_task (decoder->srcpad,
(GstTaskFunction) gst_v4l2_video_dec_loop, self,
(GDestroyNotify) gst_v4l2_video_dec_loop_stopped))
(GstTaskFunction) gst_v4l2_video_dec_loop, self, NULL))
goto start_task_failed;
......@@ -676,7 +661,8 @@ gst_v4l2_video_dec_handle_frame (GstVideoDecoder * decoder,
if (ret == GST_FLOW_FLUSHING) {
if (g_atomic_int_get (&self->processing) == FALSE)
if (gst_pad_get_task_state (GST_VIDEO_DECODER_SRC_PAD (self)) !=
ret = self->output_flow;
goto drop;
} else if (ret != GST_FLOW_OK) {
......@@ -721,7 +707,6 @@ start_task_failed:
(_("Failed to start decoding thread.")), (NULL));
g_atomic_int_set (&self->processing, FALSE);
goto drop;
......@@ -63,7 +63,6 @@ struct _GstV4l2VideoDec
/* State */
GstVideoCodecState *input_state;
gboolean active;
gboolean processing;
GstFlowReturn output_flow;
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